The Bridgewater founder talks about how his firm measures employees and economies to steer its $160 billion in investments.

How do you build the world's largest hedge fund? Bridgewater Associates founder Ray Dalio says he did it by creating a culture of "radical truth and radical transparency." Mr. Dalio's perhaps radical belief is that "everything is a machine"—including organizations and even the individual people within them. At his firm's Westport, Conn., headquarters, we are discussing the human machines at Bridgewater and the equally fascinating machine known as the U.S. economy.